Combination cracking process



May 16, 1944. IR. F. T'Row l COMBINATION CRACKING PROCESS Filed May 2o, 194s Patented May 16, 1944 CQMBINATION CRACKING PROCESS Richard VE'. Trcw,

Lawrenceville, Ill., assigner to The Texas Company, New York, N. Y., a corporation of Delaware Application May 20, 1943, Serial 1210.481685 (Cl. 19E-49) 9y Claims.

This invention relates to combination cracking processes for the production of gasoline from higher boiling hydrocarbon oils and contemplates certain improvements in combination cracking, flashing and coking.

In accordance with the invention the more highly cyclic products of conversion are segregated for separate cracking and for the production of synthetic or polymer fuel oil, While the coking is restricted essentially to residual products of less cyclic character. In recycling cracking processes, as the cracking operation proceeds, certain high boiling constituents of a highly cyclic nature tend to accumulate in the system. These products of conversion may be conveniently referred to as heavy gas oil constituents as distinguished from intermediate or light gas oil fractions of the conversion products. The heavy gas oil products of conversion are much more refractory on the basis of conversion to gasoline than are the lighter gas oil products of conversion in that the heavy cyclic constituents produce, upon cracking, relatively large yields of gas for a given yield of gasoline, as compared to the gas yield produced in cracking the light gas oil. Moreover, the residual products formed in the cracking of these high boiling constituents constitute relatively poor material for coking because of the relatively high yield ratio of gas to gasoline and gas oil. Furthermore, the highly 3 cyclic or aromatic character of these residual products of conversion makes them much more suitable for fuel oil blending purposes than virgin or less cyclic stocks. The light gas oil stocks produce, upon cracking, relatively small amounts of residual products and by keeping the light gas oil fractions, which are recycled to a cracking zone, free from the higher boiling, more cyclic gas oil constituents, higher rates of cracking per pass can be maintained in the light gas oil cracking Zone. In my process the segregation of fractions is so made that the coking is restricted to the coking of the relatively small amount of residual products formed in the conversion of the light gas cil and to the residual products produced in the cracking of raw petroleum residual stocks while the more highly cyclic constituents are utilized in operations in which polymer fuel oil is produced.

In practicing the invention light gas oil is subjected to cracking in a recycling cracking Zone by passage through a heating zone wherein it is subjected 'to a relatively high rate of cracking per pass, the heated effluent is combined with petroleum residual stock and the mixture subjected to pressure cracking in a succeeding cracking zone. The latter cracking zone includes a separating zone in which vapors are separated from residue. This residue includes the relatively small quantity of residual constituents formed in the cracking of the light gas oil together with the viscosity-broken crude residue. This residue is subjected to coking. The separated vapors are combined with the products produced in cracking the heavy gas oil and the commingled products are subjected to separation in a high pressure separating zone. The vapors in this zone are subjected to dephlegmation under relatively high temperature conditions with the result that any entrained tarry matters and high boiling polymer products contained in the vapors are combined with the residue produced in the separating Zone. The overhead vapors from this separating Zone are subjected to fractionation to separate the desired gasoline or naphtha product from higher boiling reflux condensate which is cycled to the cracking Zone. Preferably the vapors from the separating zone are first dephlegmated with a crude petroleum residual stock to form a mixture of reflux condensate and unvaporized residue which is passed through a heating zone and cornbined with the light gas oil undergoing cracking and the vapors, after this dephlegmation, are further fractionated to recover the gasoline or naphtha distillate and the light gas oil which is cycled to the cracking zone. The residue produced in the high pressure separating Zone is flashed and refractionated under lower pressure, being preferably refractionated with the vapors from the coking operation so as to segregate a synthetic polymer fuel oil and a heavy gas oil fraction which is directed to the heavy gas oil cracking zone. In this Way the heavy gas oil constituents, or highly cyclic products of conversion, are removed from the light gas oil cycle of operations and are subjected to a separate cracking cycle in which a synthetic or polymer fuel is produced. Thus the components best adapted for the production of the polymer fuel are segregated for treatment in one cycle of the system, While the concentration of heavy polymers in the light gas oil system is largely avoided and the delivery of the higher boiling, more highly cyclic materials to the coke drum is held at the minimum.

An important feature of my combination process is a high degree of flexibility so that the yield of coke and polymer fuel may be readily varied in accordance with market conditions.

The invention will be more clearly understood from the following description and from the accompanying diagrammatic drawing or flow diagram which illustrates a preferred embodiment of the apparatus or system for carrying out my improved combination cracking process.

Crude petroleum is charged by a pump IIJ through a heat exchanger II in which the oil is preheated by heat exchange with hot products from the system and is directed thence through a heating coil I2 positioned in furnace I3, wherein the oil is heated to the desired distilling temperature, after which it is passed to a fractionator I4. It is often advantageous to interpose a separator (not shown) between the heat exchanger II and furnaceheating coil I2 for the purpose of ashing off the lighter gasoline constituents as well as any normally gaseous constituents that may be contained in the crude and then heat the stripped crude in the coil I2 to the desired distilling temperature. In the fractionator I4 the crude is separated into a residual fraction, withdrawn through a line I5, and vapors, which are subjected to fractionation in the upper sections of the fractionator to obtain the cuts or fractions desired, such as gas oil, kerosene, heavy naphtha and gasoline. In the fractionation indicated in the drawing, the vapors are fractionated to obtain a higher boiling condensate collected in tray I6, a naphtha fraction collected in tray I1 and an overhead vapor fraction which is condensed in a cooling coil I8 and collected in a distillate receiver I9 as light gasoline.

Referring now to the cracking portion of the system, a heating coil 2U is disposed in a furnace 2| adapted to subject the oil to a cracking temperature. The heated effluent from the coil 29 passes through a transfer line 22 to a reaction chamber 23. In practice one or more reaction chambers may be employed. As illustrated, the entire eiiluent from the reaction chamber 23 is delivered through a transfer line 24 to a second reaction chamber 25. The reaction chambers 23 and 25 are insulated to reduce heat loss and are adapted for subjecting the oil to cracking temperature under superatmospheric pressure. Separation of vapors from liquid residue takes place in the reaction chamber 25 and the separated vapors pass through a vapor line 26 to a primary dephlegmator 21 which also constitues a separating zone for the separation of additional cracked products as will be explained hereinafter. Separated vapors from the combination dephlegmator and separator 21 pass through a vapor line 28 to a fractionator 29. The crude residue, which is withdrawn through line I5 from the tower I4, is directed by a pump 30 to the fractionator 29 and serves to dephlegmate the vapors therein, resulting in the production of a mixture of reiiux condensate and unvaporized crude residuum which is withdrawn from the fractionator 29 and directed by a pump 3| through a line 32 to a heating coil 33 disposed in a furnace 34. The equiflux type of furnace is indicated diagrammatically in the drawing since this furnace is particularly adapted for heating residual stocks to high cracking temperatures without unduly prolonging the time element in the heating coil. The effluent from the heating coil 33 is delivered through a transfer line 35 to reaction chamber 23 for further cracking therein in contact with the heated eiiluent from the coil 2B. The dephlegmated vapors from the fractionator 29 pass through a vapor line 35 to a fractionator 31 wherein fractionation is conducted so as to separate an overhead product of desired endpoint from higher boiling reux condensate. The reflux condensate is withdrawn through a line 38 and directed by a pump 39 and line 40 to the heating coil 29 wherein it is subjected to conditions of high cracking per pass. The overhead vapors pass from the fractionator 31 to a condenser coil 4I thence to a distillate accumulator or gas separator 42 wherein the gasoline distillate is collected. This distillate may be directed by a pump 43 to a rectifying column 44 wherein it may be subjected to stabilization to produce a gasoline product of desired vapor pressure, the rectified product being withdrawn through line 45.

Referring now to the coking feature of my process, liquid residue is withdrawn from the reaction chamber 25 through a line 46 and pressurereducing valve 41 and is delivered through a line 43 to a coking drum 49. Liquid is prevented from accumulating in the cracking chambers 23 and 25 by the rapid withdrawal of residue through the line 46 and in order to accomplish autogenous coking by mere flashing a small portion of the vapors is included with the residue withdrawn through line 46 so as to effect conversion to a coke residue in the coking chamber 49 without the application of heat to the coking chamber other than that of the hot stream entering from the cracking chamber 25. In practice a plurality of coking drums 49 are employed so as not to interrupt the continuity of the complete combination process for the purpose of coke removal.

The evolved vapors from the coking drum pass through a vapor line 5I) to a dephlegmator 5I. This dephlegmator is provided with a primary dephlegrnating section 52, which receives the vapors from the coking drum, and a secondary fractionating section 53, separated from each other by a condensate-collecting tray 54. The liquid product produced in the dephlegmator and separator 21 is withdrawn through a line 55 and pressure-reducing valve 58 and delivered to the dephlegmating section 52 for fractionation and dephlegmation therein together with the vapors from the coking operation.

The higher boiling condensate or straight-run gas o-il, obtained in the fractionation of the crude oil and collected in tray I6 of tower I4, is directed by a pump 51 through a line 58 to the fractionating section 53 for refractionation therein together with the dephlegmated vapors obtained from flashing the bottoms of tower 21 and from the coking operation. The reflux condensate collected in tray 54 may be conveniently referred to as heavy gas oil; it wil1 include condensed high boiling fractions produced in the cracking and coking operations and will contain hydrocarbons of a highly cyclic nature. The fraction may also include some high boiling straight gas oil constituents depending upon the boiling range of the cut collected in tray I6. The fraction is withdrawn through a line 59 and directed by a pump 60 to a heating coil 6I disposed in a furnace 62 adapted for heating the oil to a cracking temperature. The effluent from the coil 6I is discharged through a transfer line E3 to the separating and dephlegmating tower 21 wherein the residual products of cracking are separated and the separated vapors subjected to dephlegmation together with the vapors from the cracking chamber 25.

The cycle of operations as between the separator 21, the dephlegmator 5I and the cracking coil 6I serves the function of segregating certain higher boiling components produced in the cracking and coking operations and for the cracking of these components while: at the same time keeping them' out of the residual fraction which is delivered. from the cracking. chamber 25 tothe coking drum 49. As: stated, these high boiling' constituentsV that areI thus segregated' are rich in cyclic hydrocarbons. When these constituents are subjected to cracking they: produce relatively large yields of polymer tars valuable .for liquid fueloil, much higher' yields for example than are produced by the cracking of the light or intermediate gas oil, such as is withdrawn from tower 31, and subjected to cracking in coil 20. On the other hand, these heavy cyclic hydrocarbons are not sol well adapted for coking because the coking of these hydrocarbons produces relai-j 1 tively high yields of gas and, moreover; the gas.

oil product from such coking is inferior as a cracking stock. The cracking of the heavycycli'c condensate segregated in tray 54 functions, to

,is withdrawn from the cracking chamber 25 for coking, consists of components produced in the cracking or viscosity breaking and vaporization of the crude residue. These components are well adapted for coking since they yield, upon coking, smaller proportions of gas as compared to the gasoline and gas oil yield than are produced by the coking of a straight polymer tar, and, more'- f over, the gas oil product is well adapted for'further cracking.

The overhead vapors from the dephlegmator 5| pass through a cooler or condenser'64 adapted to condense all the liquid components and preferably the greater portion of the higher boiling vnormally gaseous hydrocarbons, such as C3 and C4 hydrocarbons. The cooled products pass to an absorber 65. A liquid-absorbing medium may advantageously be supplied for theA absorber 65 by withdrawing a portion of the hot condensate from line 38, directing the withdrawn portion through a reboiler coil 66 in the stabilizer 44, further cooling this condensate in a cooler61 and passingV the coo-led condensate to the absorber 6-5. The scrubbed gases leave the absorber through a line 68 and the liquid component, which consists essentially of light or intermediate gas oil constituents and gasoline together with such portion of the normally gaseous hydrocarbons as may be desired, is withdrawn from the absorber and directed by a pump 39 and line 10 to the tower 31 for refractionation therein. In this- Way the gasoline from the absorber is combined with the other gasoline vapors which pass overhead from the tower 31 andare collected as a distillate in the accumulator 42; while the gas-oil con.,- stituents from the absorber are combined with the reflux condensate which is Withdrawn through line 38.

' The residue produced in the separating zone 52 is withdrawn through a line 1|. This residue consists essentially of synthetic or polymer tar. It will be seen that it is composed of the residual fraction withdrawn from dephlegmator 21 and subjected to flashing andfurther fractionation in dephlegmator 52 together with the higher boiling constituents condensed from the vapors from the coking operation. The residual fraction withdrawn from dephlegmator 21 is composed of tar or residue produced. in theK recycling: cracking of thea heavy gasoil and of such tarry orhigh boiling componentslasA may be condensed out; of' the vapors from thev cracking still 25. The residue withdrawn through line 1ly thus constitutes an excellent fuel oil product. Itmay be withdrawn and utilized as suchor, if desired, may bedirected through a line 12 and pressure-reducing valve 13 to a flash drum or tar stripper 14 for further distilling under a lower pressure than obtains in the tower 5i.v The residue is preferably flashed under a pressure approximating atmospheric or even at subatmospheric pressure. The reduced fuel is withdrawn through a line 15 while the flashed vapors are condensed in a cooling coil 1B and the distillate is collected in an accumulator 11. In order to put this distillate back into the system for further cracking it is advantageously directed by a pump 18 through line 19 to the dephlegmator 21 to'serve. as a cooling medium iorcontrolling the temperature of the vapors in the vapor line 28. A portion of the flashed distillate may be directed through a branch line 80 to serve as a cooling reux for the dephl'eg mator 52. 3l' so that a portion of the liquid product from the absorber may be directed to the dephlegmator 21. This liquid, as well as the ashed distillate, will normally be substantially completely vaporized in the tower 21 and will pass with the vapors to the towers 29 and 31. The flash condensate from tank 11 will be largely, if not completely, vaporized inthe tower 21, although when applying vacuum ashing in the drum 14 certain heavy fractions in the'ashed distillate may descend through the tower 21 to be combined with the residual' fraction which is withdrawn through line 55 and subjected to refractionation in the dephlegmator i2 While the residual fraction, withdrawn from the dephlegmator 52 through line 1I, is normally and most advantageously used as a liquid fuel product, this fraction or a portion thereofv may be subjected to further cracking or coking at times of reduced demand for vfuel oil or of increased demand' for coke. For this purpose residue may be withdrawn from line 1l through a branch line 82 and is directed by a pump 83 through a line 84 either through branch line 85 to cracking chamber 23 or through branch line 86 to the cracking chamber 25, being preferably introduced into the latter chamber through a ringspray pipe 81 which serves to direct the residue in a down-owing film on the wall of the reaction chamber. The components of the introduced residue, which are collected in the liquid residue at the bottom of chamber 25, are subjected to coking in the coke drum 49. A portion of the bottoms from evaporator 52 may be directed through a branch line 88 to the evaporator 21 for reuxing purposes.

The. straight run naphtha fraction is withdrawn from tray I1 of the crude fractionator and is directed by a pump 89 to a heating coi] 90 disposed in a furnace 9i adapted to subject the gasoline constituents to temperatures adequate to eiect reformation of the components of increased anti'- knock quality. The eluent from the coil Spasses through a line 92 to the separating and dephlegmating tower 21 wherein this light stream is utilized effectively to increase the evaporating effect on the other products which are admittedto this chamber.

In practicing the invention the crude oilis-frac tionated, preferably at pressures approximating The line 10 may have a` branch line `cracking coil 33.

4 atmospheric under temperatures adapted to obtain a gas oil out preferably of wide boiling range and high endpoint, and this gas oil cut is refractionated in the low pressure evaporating tower to separate heavy gas oil constituents from lighter or intermediate constituents so that the higher l'boiling constituents may be directed to the cracking coil 6I while lower boiling constituents will be collected in the absorber and then sent to the fractionating portion of the light or intermediate gas oil cracking system. The cracking of the composite streams, which are subjected to crackand, in any case, the pressure in the dephlegmator -21 should be materially higher than that of the dephlegmator i. Relatively high temperatures are maintained throughout the tower 21, the minimum top temperature being about 800 F. In the tower 29 the top temperature should not be permitted to fall below around 760 F.780 F. and should preferably be held close to 800 F., while in the tower 31 the bottom temperature should be held around 700 F. The pressure in :the coke drum should be materially lower than that obtaining in the cracking chambers and ordinarily will be within a range of about 175 P. S. I. to 25 P. S. I.; the higher the yield of polymer fuel desired the lower should be the pressure in the coke drum. Pressures below 25 P. S. I. are not recommended since 25 P. S. I. is Aabout the lower limit for satisfactory absorption and recovery of condensate from the coke drum gases. A heavy fraction, withdrawn from the tray 54, is collected at temperatures of` the order of 70D-800 F. and is subjected to cracking at temperatures in excess of 900 F. under conditions to eiTecta cracking per pass of -20%.

In an example of the invention crude oil is heated to 700 F. and fractionated to obtain a light gasoline, a heavy naphthe. cut, a wide-boil ing gas oil cut'and a 20 gravity residuum. The cracking coils and 33 are each maintained at an outlet temperature of 930 F. Thereaction chambers 23 and 25 are held at 400 P. S. I. with-a top temperature in the chamber 25 of 880 F. The high pressure evaporator 21 is maintained with a bottom temperature of 850 F. and a top temperature of 830" F. The crude residuum is refluxed in the tower 29, having a top temperature of. 800 F. The mixture of unvaporized crude residue and reflux condensate is withdrawn from the tower 29 at a temperature of 815 F. and directed to the Reux condensate from tower 31 is withdrawn at a temperature of 720 F. and 'directed to the cracking coil 20. A mixture -of cracked residue and vapors withdrawn from cracking chamber 25 is flashed to coke in the coking drum which is maintained under a pressure of 40 P. S. I. and with a vapor outlet temperature of 820 F. The bottoms from the high pressure evaporator 21 are withdrawn at a temperature of 850 F. and flashed into the low pressure evaporator from which residue is withdrawn at a temperature of 800 F. The condensate from tray v5f! is withdrawn at a temperature of 700 F. and

subjected to cracking in the coil 6| with an outlet temperature of 970 F. 'I'he overhead from the low pressure tower 5l is cooled to a temperature .of'90 F. and delivered to the absorber which is maintained under a pressure of 25 P. S. I. The liquid product from the absorber is refluxed in the tower 31.

If desired, the bottoms from tower 29 may be combined directly with the eiiluentfrom heating coil 20, but generally speaking it is preferable to pass the bottoms through a heating coil prior to commingling with the products from the heating coil 20. The heating of the bottoms, prior to admixture with the products from the light gas oil cracking coil, provides exibility for charging a. wide variety of charge stocks and permits obtaining the desired soaking temperature in the reaction chambers without overheating the oil passing through the coil 20.

The iiexibility of my combination cracking process is exemplified particularly in the ability vto regulate the relative proportions of coke and polymer fuel produced. The polymer fuel oil production can be reduced by raising the temperature at the top of the high pressure evaporator l21, by raising the temperature of the lowpressure evaporator 52, and'by raising the pressure in the coke drum. Further decreases in polymer tar production can be obtained by directing portions of the bottoms from the low pressure evaporator 52 to the coke drum by way of either or both of the cracking chambers 23 and 25; but this practice should be resorted to only in case of a very low demand for fuel oil since the bottoms from evaporator 52 constitute the least desirable coking stock.

Although a preferred embodiment of the invention has been described herein, it will be understood that various changes and modifications may be made therein, while securing to a greater or less extent some or all of the benefits 0f the invention, without departing from the spirit and scope thereof.

Iclaim:

1. In the cracking of hydrocarbon oils the process that comprises passing condensate oil through a heating zone wherein it is subjected to a cracking temperature, combining the heated eliuent from` said heating zone i with crude residuum stock, subjecting the combined constituents to cracking and separating the resultant cracked products into vapors and liquid residue in a separating zone maintained under superatmospheric pressure, passing the separated vapors to a separating and'dephlegmating zone maintained under superatmospheric pressure, subjecting a higher boiling condensate oil to cracking temperature under superatrnospheric pressure in a second heating zone, directing the resultant cracked products to said separating and dephlegmating Zone wherein separation of vapors from liquid residue takes place and wherein the vapors are subjectedto dephlegmation, subjecting the dephlegmated vapors to further fractionation to separate reflux condensate from lighter fractions, recyclingsaid reux'condensate to the firstmentioned heating zone, withdrawing liquid residue from the first-mentioned separating zone and subjecting it to coking, flashing liquid residue from the aforesaid separating and dephlegmating Zone into a` lower pressure dephlegmating zone, directing the evolved vapors from the coking operation into said lower pressure dephlegmating zone, subjecting'the vapors from the lower pressure dephlegmating zone to further fractionation to separate a high bolling reux condensate from lighter fractions, and directing said high boiling reflux condensate pto said second heating zone.

2. In the cracking of hydrocarbon oils the process that comprises passing condensate oil through a heating zone wherein it is subjected to a cracking temperature, passing a mixture formed as hereinafter specied through ya second heating Zone wherein it is subjected to a cracking temperature, combining the eiuent from said heating zones, subjecting the combined constituents to cracking and separating the resultant cracked products into vapors and liquid residue in a separating zone maintained under superatmospheric pressure, passing the separated vapors to a separating 'and dephlegmating zene maintained under s uperatmospheric pressure, subjecting a higher boiling condensate oil t cracking temperature under superatmospheric pressure in a third heating zone, directing the resultant cracked products to said separating and dephlegmating zone wherein separation of vapors from liquid residue takes place and wherein the vapors are subjected to dephlegmation, dephlegmating the dephlegmated vapors with a residual oil charging stock to produce a mixture of reflux condensate and unvaporized charging stock and utilizing said mixture as the aforesaid mixture passedto said second heating zone, subjecting the vapors thus dephlegmated rto further fractionation .to separate areflux condensate from lighter fractionsrec yc1ing said reux condensate'to the rst-mentioned heating zone, withdrawing liquid residue from the first-mentioned separating zone and subjecting it to coking, flashing liquid residue from the aforesaid separating and dephlegmating Zone into a lower pressure dephlegmating zone, directing the evolved vapors from the coking operation into said lower pressure dephlegmating Zone, subjecting the vapors from the vlower pressure dephlegmating zone to further fractionation to separate a high boiling refiux condensate from lighter fractions, and directing said high boiling reflux condensateto said third heating-zone.

` V3. 'In the cracking of hydrocarbon oils lthe process that comprises passing'icondensate oil-th-riugh a heating 'zone 'whereinsitis subjected Yto acrack ing temperature, combining the I-heated `eiiluent from 'said heating-zone with crudef-residuumstock, subjecting the -combined constituents to cracking in a cracking Avzone comprising va.separating Zone wherein vaporsseparate from liquid residue and wherein liquid is prevented from accumulating, passing the separatedvaporsto aseparating and dephlegmating zone maintained under super-atmospheric pressure, subjecting a higher iboiling condensate oil Vto cracking ,temperature under superatmospheric pressure .in va.second heating zone, directing the f resultant j, crackedlproducts to said separatiingrand dephlegmating vzone wherein ,separation vof vapors from liquidresidue takes place and wherein .the vapors are subjected to dephlegmation, subjecting the ,dephlegmated vapors to further. fractionation to separate vreflux condensate .from l lighterifractions, recycling vsaid reiiux condensate to the first-mentioned heating zone, withdrawing liquid fresidue from the rstmentioned separatingzone 4tcgether with a sufficient portion of the vapors to -eiect autogenous coking and hashing the residue and vapors in a lower pressurecoking zone to effect conversion to coke, ashingliquid residue from the aforesaid 4separating and dephlegmating Zone into `a lower pressure dephlegmating zone, directing the evolved vapors from the eckige Operatiep inte said lower pressure dephlegmating zone, subjecting the vapors from the lower pressure 01e-, phlegmating zone to further fractionation to separate a high boiling reiiux condensate vfrom lighter fractions, and directing said high boiling reflux condensate to said second heating zone.

4. In the cracking of hydrocarbon oils the proc.- ess that comprises passing condensate oil through a heating zone wherein it is subjected to a cracking temperature, passing a mixture formed as hereinafter specified through a second heating zone wherein it is subjected to a cracking temperature, combining the eiiluent from said heating zones, subjecting the combined constituents to cracking in a cracking z one comprising'a separating zone wherein vapors separate Ifrom liquid residue and wherein liquid is prevented from accumulating, passing the separated vapors to Aa separating and dephlegmating zone maintained under superatmospheric pressure, subjecting a higher boiling condensate oil to cracking vteniperature under superatmospherie pressure -ip e third heating zone, .directing the resultant cracked products to said separating and dephlegmating zone `wherein separation Qf vapors .from .liquid residue takes place and wherein the vapors are subjected to dephlegmation, dephlegmaiing the dephlegmated vapors with a 4residual eil .ehergine Ystock to produce a ,mixture 40f reliX e09- densate and unvaporizedfehareine Steek and utilizine said mixture as the aforesaid mixture passed tesaid second heating subieetihg the vapers `rbus A-dephleemated `te further freeftionaticn to .seperate e reflux condensate from lighter fractions, recycling `,Said reuX eendensate to ,the inst-mestiere@ Vheating Zone, Withdrawins liquid residuelfrem .the -irst-mentioned separatinezone,tpcether with afsueientperfen of the vapors to effect -euiegeneeus @elsing .and Hasi/lifting the residue all@ -VaPOlS in ,a 10WC1` DTS- sure cokirlg Zone to effect conversion to coke, flashing liquid residue from the aforesaid separating and dephlegmating zone into a lower. pressure dephlegmating zone, directing the v evolved vapors from the coking operation into said lower pressure dephlegmating zonesubj'ecting the vapors from the lower pressu-redephlegmating zone to further fractionation vto separate a. high boil'- ing reux condensate from lighter fractions; and directing saidhigh boiling redux condensate to said thirdhe'ating Zone. 5. vIn the cracking of hydrocarbon oils the process that comprises passing condensate oil through a heating zone wherein it is subjected to a cracking temperature, passing a mixture formed as hereinafter specied through a second heating zone wherein it issubjected to va 4cracking temperature, combining the eiuent from saidheating zones, subjecting the combined constituents tocracking ina cracking z one comprising a separating zone wherein vapors separate from liquid residue and whereinliq d is prevented Yfrom accumulating, passing the vseparated vapors to a separating and dephlegmating zone maintained under superatmospheric pressure, subjecting a higher `boiling condensate oil to cracking -tem- .ciichargine ,steek .to .produce e mixture 0f redux llighter fractions, l flux condensate to said third'heating zone, and

condensate and unvaporlzed charging stock and utilizing said mixture as the aforesaid mixture passed to saidl second heating zone, subjecting the vapors thus dephlegmated to further fractionation to separate a reflux condensate from lighter fractions, recycling said redux condensate to the first-mentioned heating zone, withdrawing liquid residue from the first-mentioned separating zone together with a sufficient portion of the vapors to effect autogenous coking and flashing the residue and vapors in a lower pressure coking zone to effect conversion to coke, flashing liquid residue fromv the aforesaid separating and dephlegmating zone into a lower pressure separating and dephlegmating zone wherein separation of vapors from liquid residue takes place,A directing the evolved vapors from the coking operation into said lower pressure dephlegmating zone, withdrawing liquid residue from the lower pressure separating and dephlegmating zone and reluxing a portion thereof in the higher pressure separating and dephlegmating zone, subjecting the vapors from the lower pressure dephlegmating zone to further fractionation to separate a high boiling reflux condensate from lighter fractions, and directing said high boiling reflux condensate to said third heating zone.

6. InY the cracking of hydrocarbon oils the process that comprises passing condensate oil through a heating zone wherein it is subjected to a 4cracking temperature, passing a mixture formedas hereinafter specified through a secondI heating zone wherein it is subjected to a cracking temperature, combining the effluent from said heating zones, subjecting the combined constituents to cracking and separating the resultant cracked products into vapors and liquid residue in a separating zone maintained under superatmospheric pressure, passing the separated vapors to a separating and dephlegmating zone maintained under superatmospheric pressure, subjecting a higher boiling condensate oil to cracking temperature under superatmospheric pressure in a third heating zone, directing the resultant rcracked products to said separating and dephlegmating zone wherein separation of vapors from liquid residue takes place and wherein the vaporsare subjected Vto dephlegmation, dephlegmatng the dephlegmated vapors with a residual oil charging stock to produce a mixture of reflux condensate and unvaporized charging stock and utilizing said mixture as' the aforesaid vmixture passed to said second heating zone,sub jecting the vapors thus'dephlegmated to further fractionation to separate a reflux condensate from lighter fractions, recycling said reux con densate `to the first-mentioned heating zone, withdrawing liquid residue from the first-mentioned separating zone and subjecting it to 'coking, flashing liquid residue from the aforesaid 'separating and dephlegmating zone into a lower pressure dephlegmating zone, directing the evolved vapors from the coking operation into said lower pressure dephlegmating zone, subjecting the vapors from the lower pressure dephlegmating zone to further fractionation to separate a high boiling reflux condensate from directing said high boiling recombining lighter fractions thus Aobtained with vapors Afrom said cracking operations for fractionation therewith. 7. In the cracking of hydrocarbon oils the process 'that through a heating zone wherein it is subjected to comprises passing condensate oil "Is a vcracking temperature, combining the heated effluent from said heating zone with crude residuum stock, subjecting the combined constituents to cracking and separating the resultant cracked products into vapors and liquid residue in a separating zone maintained under super-4 atmospheric pressure,v passing the separated vapors to a separating and dephlegmating zone maintained under superatmospheric pressure, subjecting a higher cracking temperature under superatmospheric pressure in a second heatingv zone, directing the resultant cracked products to said separating and dephlegmating zone wherein is effected a separation of vapors from a liquid residue consisting essentially of polymer products of cracking, subjecting the dephlegmated vapors to further fractionation to separate reflux condensate from lighter fractions, recycling said reflux condensate to the first-mentioned heating zone, ashing the residue from said separating and dephlegmating zone to separate a polymer fuel oil, subjecting the flashed vapors to fractionation to separate a high boiling reflux condensate from lighter fractions, directing said high boiling reflux condensate to said second heating zone, and flash distilling the residue from the first-mentioned separating zone and combining resultant flashed distillate with vapors from the aforesaid cracking zones for fractionation therewith.

8. In the cracking of hydrocarbon oils the process that comprises passing condensate oil through a heating zone wherein it is subjected to a cracking temperature, fractionating crude petroleum to separate residual constituents from condensate fractions, combining the heated effluent from said heating zone with residual constituents from the crude petroleum, subjecting the combined constituents to cracking and separating the resultant cracked products into vapors and liquid residue in a separating zone maintained under superatmospheric pressure, passing the separated vapors toa separating and dephlegmating zone maintained under superatmospheric pressure, subjecting a higher boiling condensate oil to cracking temperature under superatmospheric pressure in a second heating zone, directing the resultant cracked products to said separating and dephlegmating zone wherein separation of vapors from liquid residue takes place and wherein the vapors are subjected to dephlegmation, subjecting the dephlegmatedvapors to further fractionation to separate reflux condensate from lighter fractions, recycling said reux condensate to the first-mentionedheating zone, withdrawing liquid residue from the rst-mentioned separating zone and subjecting it to coking, flashing liquid residue from the aforesaid separating and dephlegmating zone into. a lower pressure dephlegmating zone, directing the evolved vapors from the coking operation into said lower pres-A sure dephlegmating zone, subjectingA the vapors from the lower pressure dephlegmating zone and condensate fractions lfrom lthe crude petroleum to fractionation in a succeeding fractionating zone to separate a high boiling vfraction-from lower boiling fractions comprising Aconstituents higher boiling than gasoline, directing said high boiling reflux condensate to said second heating zone, and combining constituents higher boiling than gasoiine, obtained from said succeeding fractionating zonev with the reflux condensate being recycled to said first-mentioned heating zone.

boiling condensate oil tov 9. In the cracking of hydrocarbon oils the process that comprises passing condensate oil through a heating zone wherein it is subjected to a cracking temperature, fractionating crude petroleum to separate naphtha and gas oil fractions from higher boiling residual constituents, combining the heated efnent from said heating zone with residual constituents from the crude petroleum, subjecting the combined constituents to cracking and separating the resultant cracked products into vapors and liquid residue in a separating zone maintained under superatmospheric pressure, passingfthe separated vapors to a separating and dephlegrnating Zone maintained under superatmospheric pressure, subjecting a higher boiling condensate oil to cracking temperature under superatmospheric pressure in a second heating zone, directing the resultant cracked products to said separating and dephlegmating zone wherein separation of vapors from liquid residue takes place and wherein the vapors are subjected to dephlegmation, subjecting naphtha fractions from the crude petroleum to conditions of temperature and pressure to effect the reforming thereof, directing the resultant reformed products to said separating and dephlegmating zone, subjecting the dephlegmated vapors to further fractionation to separate reflux condensate from lighter fractions, recycling said reux condensate to the first-mentioned heating zone, withdrawing liquid residue from the rstmentioned separating zone and subjecting it to coking, flashing liquid residue from the aforesaid separating and dephlegmating zone intov a lower =pressure dephlegmating zone, directing the evolved vapors from the coking operation into said lower pressure dephlegmating zone, subjecting the vapors from the lower pressure dephlegmating Zone and condensate fractions from the crude petroleum to fractionation in a succeeding fractionating zone to separate a high boiling fraction from lower boiling fractions comprising constituents higher boiling than gasoline, directing said high boiling reux condensate to said second heating zone, and combining constituents higher boiling than gasoline, obtained from said succeeding fractionating zone with the reflux condensate being recycled to said first-mentioned heating zone.

RICHARD F. TROW. 

